Briquette for producing aluminum-silicon

ABSTRACT

The briquette of the invention comprises the following components in the following weight percentage: carbonaceous reducing agent, 30 to 40; alumina, 4 to 25; kaolin, 8 to 40 and disthene sillimanite, the remainder.

United States Patent [191 llinkov et a1.

1 1 BRIQUETTE FOR PRODUCING ALUMINUM-SILICON [76] Inventors: Dmitry Vladimirovich llinkov, ulitsa Tregubenko, 13, kv. 5; Pavel Ilich Volpin, prospekt Lenina, 210, kv. 16; Vasily Petrovich Rumyantsev, ulitsa Sportivnaya, 25, kv. 62; Stanislav Arsenievich Artemenko, ulitsa Stalevarov, a, kv. 27; Miro Alivoivodich, ulitsa let Sovetskoi Ukrainy, 46, kv. 21; Raisa lvanovna Ragulina, prospekt Metallurgov, 21, kv. 40, all of Zaporozhie; Vasily Grigorievich Zadorozhny, ulitsa Gornyakov, 18; Viktor Viktorovich Varen, ulitsa Gornyakov, 17, both of Volnogorsk Dnepropetrovskoi oblasti; Boris Ivanovich Emlin, ulitsa Dzerzhinskogo, 22, kv. 9, Dnepropetrovsk; Mikhail Ivanovich Gasik, Zaporozhskoe shosse, 6, kv. 9, Dnepropetrovsk; Spiridon losifovich Khitrik, prospekt Gagrina, 2, kv. l2, Dnepropetrovsk; Nikolai Semenovich Klimkovich, ulitsa 40 let Oktyabrya, l, kv. 18, Dnepropetrovsk; Anatoly Yakovlevich Novikov, ulitsa Stasova, 26, kv. l, Dnepropetrovsk; Ljudmila Ivanovna Gasik, Kosmichesoke shosse, 19a, kv. 22, Zaporozhie, all of USSR.

[22] Filed: Sept. 18, 1972 July 1,1975

21 Appl. No.: 289,945

[30] Foreign Application Priority Data Sept. 17, 1971 U.S.S.R. 1695232 [52] US. Cl /10 R; 75/.5 R; 75/148 [51] Int. Cl. C22c 21/02 [58] Field of Search 75/148, 10 A, 10 R, .5 R

[56] References Cited UNITED STATES PATENTS 1,686,206 10/1928 Flodin 75/10 R 1,741,920 12/1929 Curtis 75/10 R 2,054,427 9/1936 Kirsebom 75/148 X 2,627,458 2/1953 Cichty.... 75/148 X 3,655,362 4/1972 Schmidt 75/10 R FOREIGN PATENTS OR APPLICATIONS 748,334 9/1951 United Kingdom 75/10 R Primary ExaminerWinston A. Douglas Assistant Examiner-John F. Niebling Attorney, Agent, or FirmHolman & Stern [57] ABSTRACT The briquette of the invention comprises the following components in the following weight percentage: carbonaceous reducing agent, 30 to 40; alumina, 4 to 25; kaolin, 8 to 40 and disthene sillimanite, the remainder.

2 Claims, No. Drawings 1 BRIQUETTE FOR PRODUCING ALUMINUM-SILICON The present invention relates to the electrometallurgy of aluminium and silicon and more particularly to a composition of briquettes used for producing aluminum-silicon by the ore reducing smelting process in an electric-arc furnaces.

In accordance with the known processes, aluminium is produced electrolytically from high-alumina bauxites (containing more than 50 per cent of A1 Silicon is produced by the ore reducing smelting process from quartzites having a low content of alumina in their composition.

Long and extensive research has been conducted all over the world to find a way to use natural aluminium silicates with aluminium and silicon as the principal elements of their composition for the production of aluminium-silicon alloys.

As a result of such research work, a process has been developed in the Soviet Union for the production of aluminum-silicon briquettes by subjecting the ore to a reducing smelting process in an electric-arc furnaces having a composition featuring enriched kaolin 3(Al- 0 2SiO but low in iron, and containing from 37 to 38 weight per cent of aluminium oxide and from 0.6 to 1.0 weight per cent of ferric oxide, and alumina containing 98 to 99 per cent of A1 0 with the use of various carbonaceous materials as redicing agents such as gas coal, petroleum coke, and the like.

The above-specified charge composition (briquettes) for the production of aluminum-silicon is, however, not free from essential disadvantages.

During the course of the ore reducing smelting pro cess, the briquettes become fused prior to the commencement of the reduction reactions due to the formation of mullite from the kaolin which proceeds according to the following schematic equation 2(Al O 2SiO --+AI O 2Si0 4Si0 at temperatures of up to l550C.

If the stock is not regulated and descends into the reducing zone and with frequent fall-ins of the charge the formation of air holes, which, on the one hand, leads to the reduced metallic phase being contaminated with a considerable quantity of unreduced briquettes and, on the other hand, to the entrainment through such holes of considerable quantities of the charge and of gaseous suboxides of aluminium and silicon.

The so-called master alloy obtained from the furnace therefore contains a considerable quantity of slags in the form of unreduced aluminium, silicon oxides and carbides. Usually the content of such slags in an alloy is from 12 to 15 weight per cent; when the alloy is decanted, these slags retain approximately the same amount of the reduced metallic phase. The total yield of the master alloy in the form of aluminum-silicon comes to from 65 to 68 weight per cent. In a subsequent conversion the consumption of electrolytic aluminium for the production of silumin is about 720 kg per ton.

The object of the present invention is to provide briquettes for the production of aluminum'silicon whose composition would be such as to allow optimal electrical and thermal conditions for the furnace operation and thereby a substantial improvement in the technical and economic characteristcs of the production of aluminum-silicon by the ore reducing smelting process through lowering the consumption figures for electric power and the main stock materials.

This said object is accomplished by the provision of a briquette for the production of aluminum-silicon by the ore reducing smelting process in electric-arc furnaces, with comprising a carbonaceous reducing agent, alumina and kaolin, with the composition of the briquette, according to the invention, additionally incorporating disthene silimanite, and the weight percentage of the components in the composition being:

carbonaceous reducing agent 30 to 40, alumina 4 to 25, kaolin 8 to 40, disthene sillimanite the balance.

The composition proposed herein is characterized by the fact that the natural aluminium silicate, namely, disthene sillimanite, contains from 10 to 20 weight per cent of disthene which has the highest thermodynamic strength as compared to other aluminium silicates and forms, upon heating, a mixture of mullite and silica which has a melting point in the liquid phase of about l810C. This circumstance allows'for the reduction of the oxides from the yet unmolten charge in the case of thorough mixing of the oxides with the reducing agent.

At the same time the present composition makes possible the reduction of aluminium and silicon to be performed in maximum amounts thereof, with the smelting process products having a diminished slag content. Moreover, with the use of the herein-proposed composition conditions are created which contribute to carbides being formed in smaller amounts thus lowering the electric conduction of the furnace and, hence, better utilization of the productive capacity of the furnace.

The use of disthene sillimanite in the composition of the briquette enhances the sintering of the charge on top of the ore heat-treating furnace due to an increase in the quantity of the mineral component in the composition of the briquettes. This contributes to a more uniform running of the furnace without the formation of air holes and the falling-ins of the charge, as well as to the stable state of the middle portion of the furnace, the latter being one of the major sources of unreduced oxides.

Laboratory tests of the present composition of the briquette have shown that with the processes for reducing the kaolin-alumina charge and of the charge incorporating the above-specified addition of disthene silimanite being run in parallel at a temperature of 1750C, the reduction of the charge having disthene silimanite is brought to considerably higher degree of completion within a shorter period of time (after minutes the reduction of the kaolin-alumina charge reaches weight per cent and is practically completed, whereas the charge having disthene sillimanite is reduced to 98 to 99.5 weight per cent).

An illustrative example of the embodiment of the present invention is given hereinbelow.

The composition of the briquettes employed was as follows (in weight per cent):

disthene sillimanite 20 kaolin 25 alumina 25 carbonaceous reducing agent 30 The charge for the briquette was prepared by maxing the components with an accuracy of 11 weightper cent in continuous-action batchers, mixing the components and subsequentlybriquetting the composition on roll 4 What is claimed is: 1. A briquette for producing aluminum-silicon by the ore reducing smelting process in an electric-arc furnace, the briquette composition comprising, in weight presses with the addition of a binder, namely alcohol- 5 per cent: sulphite lye to a humidity of 14 to 16 per cent, this carbonaceous reducing agent, 30 to 40; being followed by drying in gas-heated apron dryers at kaolin, g to 40; a temperature not above from 200 to 230C to a 1% alumina 4 to d h remainder humidity. The mechanical compression strength of the disthene mi i ellipsoid-shaped briquettes from 60 to 40 mm in size 10 2,"Th' briquette of lai 1 comprising, i i h was 120 to 180 kglcm Cent carbonaceous reducing agent, The process characteristics for the production of kaolin, 25; aluminum-silicon in a furnace with a capacity of l 1 Mw alumina, 25; and are given in the Table 1 which follows. 15 disthene sillimanite, 20.

Table Kaolin-. Briquett es alumina with disthene briquettes sillimanite 7. Power consumption per ton of v aluminum-silicon. in kWh 10800 10200 2. Consumption of stock materials per ton of aluminum-silicon, in kg: (:1) kaolin 2400 1700 (b) alumina 880 780 (c) disthene sillimanite 480 3. Consumption of electrolytic aluminum per ton of silumin, in kg 718 700 a 4. Composition of aluminum-silicon, y

weight per cent: silicon 38 37 aluminium S7 60 iron 1.6 1.5 titanium 0.65 0.65 5. Yield of aluminum-silicon,

weight per cen. 67 72 i 

1. A BRIQUETTE FOR PRODUCING ALUMINUM-SILICON BY THE ORE REDUCING SMELTING PROCESS IN AN ELECTRIC-ARS FURNACE, THE BRIQUETTE COMPOSITION COMPRISING, IN WEIGHT PER CENT, CARBONACEOUS REDUCING AGENT, 30 TO 40, KAOLIN, 8 TO 40, ALUMINA 4 TO 25, AND THE REMAINDER DISTHENE SILLIMANITE.
 2. The briquette of claim 1 comprising, in weight percent: carbonaceous reducing agent, 30; kaolin, 25; alumina, 25; and disthene sillimanite,
 20. 